Internal combustion engine



FIG. 1 is a front elevational view of the internal combustion engine showing my new design;

FIG. 2 is a rear elevational view of FIG. 1;

FIG. 3 is a right side elevational view of FIG. 1;

FIG. 4 is a left side elevational view of FIG. 1;

FIG. 5 is a top plan view of FIG. 1;

FIG. 6 is a bottom plan view of FIG. 1;

FIG. 7 is a front prospective view of FIG. 1; and,

FIG. 8 is a rear prospective view of FIG. 1. 

The ornamental design for an internal combustion engine, as shown and described. 